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The internal dynamics of a dark matter structure may have the remarkable property that the local temperature in the structure depends on direction. This is parametrized by the velocity anisotropy beta which must be zero for relaxed…

Dark matter particles form halos that contribute the major part of the mass of galaxy clusters. The formation of these cosmological structures have been investigated both observationally and in numerical simulations, which have confirmed…

Astrophysics · Physics 2009-11-05 Ole Host

The Universe contains approximately 6 times more dark matter than normal baryonic matter, and a directly observed fundamental difference between dark matter and baryons would both be significant for our understanding of dark matter…

Astrophysics · Physics 2009-11-13 Steen H. Hansen , Rocco Piffaretti

The density profile of simulated dark matter structures is fairly well-established, and several explanations for its characteristics have been put forward. In contrast, the radial variation of the velocity anisotropy has still not been…

Astrophysics · Physics 2014-11-18 Steen H. Hansen

We study velocity moments of elliptical galaxies in the Coma cluster using Jeans equations. The dark matter distribution in the cluster is modelled by a generalised formula based upon the results of cosmological N-body simulations. Its…

Astrophysics · Physics 2009-09-29 Ewa L. Lokas , Gary A. Mamon

Velocity distribution of dark matter is assumed to be isotropic in most cases, however, anisotropy is suggested in some simulations. Directional direct detection of dark matter is a hopeful way to discriminate the anisotropy of dark matter…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-10 Keiko I. Nagao

We consider the dynamics in and near galaxy clusters. Gas, dark matter and galaxies are presently falling into the clusters between approximately 1 and 5 virial radii. At very large distances, beyond 10 virial radii, all matter is following…

Cosmology and Nongalactic Astrophysics · Physics 2017-11-08 L. Albaek , S. H. Hansen , D. Martizzi , B. Moore , R. Teyssier

The velocity anisotropy of particles inside dark matter (DM) haloes is an important physical quantity, which is required for the accurate modelling of mass profiles of galaxies and clusters of galaxies. It is typically measured using the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Radoslaw Wojtak , Stefan Gottloeber , Anatoly Klypin

We use extensive measurements of the cluster A1689 to assess the expected similarity in the dynamics of galaxies and dark matter (DM) in their motion as collisionless `particles' in the cluster gravitational potential. To do so we derive…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Doron Lemze , Yoel Rephaeli , Rennan Barkana , Tom Broadhurst , Rick Wagner , Mike L. Norman

We report statistical results for dark matter (DM) velocity anisotropy, \beta, from a sample of some 6000 cluster-size halos (at redshift zero) identified in a \Lambda CDM hydrodynamical adaptive mesh refinement simulation performed with…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Doron Lemze , Rick Wagner , Yoel Rephaeli , Sharon Sadeh , Michael L. Norman , Rennan Barkana , Tom Broadhurst , Holland Ford , Marc Postman

Dark matter comprises the bulk of the matter in the universe but its particle nature and cosmological origin remain mysterious. Knowledge of the dark matter density distribution in the Milky Way Galaxy is crucial to both our understanding…

One can solve the Jeans equation analytically for equilibrated dark matter structures, once given two pieces of input from numerical simulations. These inputs are 1) a connection between phase-space density and radius, and 2) a connection…

Astrophysics · Physics 2009-11-13 Steen H. Hansen , Joachim Stadel

Direct detection of dark matter with directional sensitivity has the potential to discriminate the dark matter velocity distribution. Especially, it will be suitable to discriminate isotropic distribution from anisotropic one. Analyzing…

Instrumentation and Methods for Astrophysics · Physics 2018-05-08 Keiko I. Nagao

Dark matter haloes in cosmological N-body simulations are affected by processes such as mergers, accretion and the gravitational interaction with baryonic matter. Typically the analysis of dark matter haloes is performed in spherical or…

Cosmology and Nongalactic Astrophysics · Physics 2012-07-26 Martin Sparre , Steen H. Hansen

Although the velocity distribution of dark matter is assumed to be generally isotropic, some studies have found that $\sim\hspace{-0.1cm}25$\% of the distribution can have anisotropic components. As the directional detection of dark matter…

Cosmology and Nongalactic Astrophysics · Physics 2018-08-29 Keiko I. Nagao

The velocity distribution of dark matter is supposed to be isotropic Maxwell- Boltzmann distribution in most cases, however, its anisotropy is suggested by some simulations. We investigate conditions to give constraints on the anisotropy…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-10 Keiko I. Nagao

One can solve the Jeans equation analytically for equilibrated dark matter structures, once given two pieces of input from numerical simulations. These inputs are 1) a connection between phase-space density and radius, and 2) a connection…

Astrophysics · Physics 2015-06-24 Steen H. Hansen , Ben Moore , Joachim Stadel

Using cosmological N-body simulations we study the radial velocity distribution in dark matter haloes focusing on the lowest-order even moments, dispersion and kurtosis. We determine the properties of ten massive haloes in the simulation…

Astrophysics · Physics 2009-11-10 Radoslaw Wojtak , Ewa L. Lokas , Stefan Gottloeber , Gary A. Mamon

Using cosmological N-body simulations we study the line-of-sight velocity distribution of dark matter haloes focusing on the lowest-order even moments, dispersion and kurtosis, and their application to estimate the mass profiles of…

Astrophysics · Physics 2009-11-13 Radoslaw Wojtak , Ewa L. Lokas , Stefan Gottloeber , Gary A. Mamon

Using high-resolution non-radiative hydrodynamic simulations of galaxy clusters we obtain simple analytic formulae for DM and gas distribution in the spherical approximation. We derive fits for the DM density, velocity dispersion and…

Astrophysics · Physics 2008-11-26 Elena Rasia , Giuseppe Tormen , Lauro Moscardini
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